Surgical tool and method for extracting tissue from wall of an organ

ABSTRACT

The present invention is concerned with methods and equipment for the treatment of the eye and more particularly with an instrument to increase eye filtration and treat glaucoma. The instrument is surgical tool operated entirely by the surgeon&#39;s hands and is composed of a hand-piece and an eye-penetrating intraocular segment each having two opponent and reciprocally operating fork-like arms and blade-sharp leaves, respectively. The eye-penetrating segment is a rigid embodiment of a size to create a limbus-pointing tunnel in the cornea, penetrate the eye of a patient through a water tight incision and, in a five step dissect and extract procedure, remove from within the eye a trabecular tissue block leaving the incision to self-seal by intraocular pressure. In the same “modus operandi”, a sample tissue can be extracted from any other hollowed or parenchimatous organ.

This application is a Divisional of U.S. Ser. No. 10/135,365 filed May1, 2002, currently pending.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to surgical tools and methods and, inparticular, it concerns a surgical tool and corresponding method forextracting tissue from wall of an organ. The tool and method areparticularly suited to procedures for lowering intraocular pressure.

Glaucoma is a disease in which intraocular pressure is a causative riskfactor. It affects significant numbers of our population. The treatmentof glaucoma is usually medicinal to lower the intraocular pressure.However, medications often fail to control some forms of glaucoma. Whenfurther treatment is required, a microsurgical operative procedure isperformed.

Conventional surgical techniques for intraocular pressure reductionapproach the tissue in the angle of the eye through the conjunctiva. Theprocedure involves constructing a fistula or opening in the tissue wall,or significant thinning of the tissue in the region of the angle of theeye (sclerokeratectomy or trabeculectomy, to enhance fluid (aqueoushumor) flow from the internal portion of the eye through the newlyformed opening. This surgery encounters many complications, ranging fromloss of the volume and shape of the eye when the fistula is too largethrough to formation of scar tissue which seals down the fistula. Thelatter requires peri-operative application or injection ofanti-metabolites, harboring a significant risk of bleeding, infections,wound leaks, buttonholing or penetrating vital tissues.

A corneal approach for surgical treatment of glaucoma has been proposedby J. E. Cairns (“Clear-Cornea Trabeculectomy”, Trans Ophthalmol Soc UK1985; 104:142-5) and by R. B. Keillor et al. (“Twenty-Two Cases of ClearCornea Trabeculectomy”, Australian and New Zealand Journal ofOphthalmology 1986: 14: 339-342). While this approach shouldtheoretically offer advantages of minimizing complications due to damageto the conjunctiva, in practice, the results have been poor, primarilydue to complications associated with the typically large cornealincision.

There is therefore a need for tools and methods for reliably removing ablock of tissue from the region of the angle of the eye, including atleast some trabecular tissue, without the complications resulting fromdamage to the conjunctiva. It would similarly be useful to provide atool and method for extracting a tissue block from the wall of a holloworgan.

SUMMARY OF THE INVENTION

The present invention is a tool and method for extracting a tissue blockfrom the wall of a hollow organ.

A method for extracting a tissue block from the angle of an eye, themethod comprising: (a) forming a first elongated slit of substantiallyconstant width entering at a peripheral region of the cornea, the firstelongated slit providing a face of a self-sealing flap having a terminalangle of no more than 25°; (b) employing a tool inserted via the firstelongated slit to the limbus underlying the conjunctiva to form aplurality of additional slits so as to define the tissue block; and (c)withdrawing the tissue block along the first elongated slit such thatthe first elongated slit is temporarily elastically deformed to allowpassage of the tissue block and is then sealed by the self-sealing flap.

According to a further feature of the present invention, a secondundercut slit is formed from a first position along the first elongatedslit so as to further define the self-sealing flap.

According to a further feature of the present invention, the pluralityof additional slits includes a second undercut slit from a firstposition along the first elongated slit so as to further define theself-sealing flap and so as to form at least a proximal cut of thetissue block.

According to a further feature of the present invention, the pluralityof additional slits further includes a pair of side cuts below the firstelongated slit so as to define sides of the tissue block.

According to a further feature of the present invention, the pluralityof additional slits further includes a lower slit extending into theangle of the eye so as to at least partially define a lower side of thetissue block.

According to a further feature of the present invention, the pluralityof additional slits further includes a third slit from a second positionalong the first elongated slit distal to the first position so as toform at least a distal cut of the tissue block.

According to a further feature of the present invention, the firstelongated slit, the second undercut slit, the third slit and the sidecuts are all performed by a manually operated mechanical tool insertedalong the first elongated slit.

According to a further feature of the present invention, the firstelongated slit extends at a maximum depth sufficiently small to renderan instrument inserted therein visible through overlying tissue.

According to a further feature of the present invention, thesubstantially constant width of the first elongated slit is less than 5mm.

There is also provided according to the teachings of the presentinvention, a method for extracting a tissue block from the wall of ahollow organ and forming a self-sealing flap in tissue of the wall, themethod comprising: (a) forming a first elongated slit of substantiallyconstant width extending from an outer surface of the wall into thewall, the first elongated slit forming a face of a self-sealing flap;(b) forming a plurality of additional slits so as to define the tissueblock, the plurality of additional slits including: (i) a secondundercut slit from a first position along the first elongated slit so asto further define the self-sealing flap so as to form a terminal angleof no more than 25°, the second undercut slit additionally forming atleast a proximal cut of the tissue block, (ii) a pair of side cuts belowthe first elongated slit so as to define sides of the tissue block, and(iii) a third slit from a second position along the first elongated slitdistal to the first position so as to form at least a distal cut of thetissue block; and (iv) withdrawing the tissue block along the firstelongated slit such that the first elongated slit is temporarilyelastically deformed to allow passage of the tissue block and is thensealed by the self-sealing flap.

According to a further feature of the present invention, the firstelongated slit, the second undercut slit, the third slit and the sidecuts are all performed by a manually operated mechanical tool insertedalong the first elongated slit.

According to a further feature of the present invention, the pluralityof additional slits further includes a lower slit so as to at leastpartially define a lower face of the tissue block.

There is also provided according to the teachings of the presentinvention, a surgical tool for forming a self-sealing flap in tissue ofa wall of a hollow organ during a procedure for extracting a tissueblock from the wall, the surgical tool comprising a tool head including:(a) an elongated support element having a direction of elongation andconfigured for insertion along a first slit parallel to the direction ofelongation into the tissue of the wall; and (b) a blade elementpivotally mounted on the support element so as to be pivotable about anaxis perpendicular to the direction of elongation, the blade elementincluding a rear blade with at least one deflecting feature configuredfor forming a second slit diverging from the first slit duringwithdrawal of the tool along the first slit, thereby forming aself-sealing flap in the tissue of the wall.

According to a further feature of the present invention, a plane passingthrough the support element parallel to both the direction of elongationand the axis is referred to as a tool plane, and wherein the bladeelement is mounted on the support element via a lever mechanism, thelever mechanism being configured to allow displacement of the bladeelement from an in-plane position in which the axis lies substantiallywithin the tool plane to an out-of-plane position in which the axis isdisplaced so as to be parallel to, but removed from, the tool plane.

According to a further feature of the present invention, the levermechanism includes a pair of lever arms each having a first endpivotally engaged with the support element and a second end pivotallyengaged with the blade element.

According to a further feature of the present invention, the lever armsare configured such that, when the blade element assumes theout-of-plane position, at least part of each of the lever arms presentsa blade edge extending substantially perpendicular to the tool plane andoriented for cutting parallel to the direction of elongation.

According to a further feature of the present invention, the levermechanism further includes a lock element configured to retain the bladeelement in the out-of-plane position.

According to a further feature of the present invention, the bladeelement has a substantially planar upper surface, the lever mechanismfurther including a resilient biasing element deployed such that, whenthe blade element assumes the out-of-plane position, the biasing elementbiases the blade element to a position with the upper surfacesubstantially parallel to the tool plane.

According to a further feature of the present invention, the bladeelement further includes a front blade configured for cutting a slitparallel to the tool plane during advancing of the tool along the firstslit.

According to a further feature of the present invention, the bladeelement is referred to as the first blade element, and wherein the axisis referred to as the first axis, the tool head further including asecond blade element pivotally mounted on the support element distallywith respect to the first blade element, the second blade element beingpivotable about a second axis parallel to the first axis, the secondblade element including a rear blade with at least one deflectingfeature configured for forming an additional slit diverging from thefirst slit during withdrawal of the tool along the first slit.

According to a further feature of the present invention, the levermechanism further includes a retention element deployed such that, whenthe blade element assumes the in-plane position, the retention elementabuts a surface of the second blade element so as to limit pivotalmovement of the second blade element about the second axis and, when theblade element assumes the out-of-plane position, the retention elementis removed from the second blade element so as not to limit pivotalmovement of the second blade element about the second axis.

According to a further feature of the present invention, the elongatedsupport element includes a fork portion formed with two projecting arms,the blade element being mounted between the projecting arms.

According to a further feature of the present invention, a distalportion of each of the projecting arms is formed as a blade parallel tothe direction of elongation.

According to a further feature of the present invention, the bladeelement further includes a pair of side blades extending along amajority of a length between the front blade and the rear blade in adirection substantially perpendicular to the axis.

According to a further feature of the present invention, the bladeelement further includes an opening substantially circumscribed by thefront blade, the rear blade and the pair of side blades.

According to a further feature of the present invention, there is alsoprovided a blade control assembly including at least one abutmentelement mechanically interconnected with the elongated support elementso as to be movable relative to the elongated support element between aclosed position in which the at least one abutment element abuts theblade element so as to restrain pivotal movement of the blade elementand an open position in which the abutment element is removed from theblade element so as to allow pivotal movement of the blade element

According to a further feature of the present invention, the at leastone abutment element is implemented as a second blade assemblyincluding: (a) a second elongated support element having a seconddirection of elongation; and (b) a second blade element pivotallymounted on the second support element so as to be pivotable about asecond axis perpendicular to the second direction of elongation.

According to a further feature of the present invention, the secondblade element includes a second front blade configured for cutting aprimary slit parallel to the second axis during advancing of the toolinto the tissue of the wall, and a second rear blade with at least onedeflecting feature configured for forming a secondary slit divergingfrom the primary slit during withdrawal of the tool along the firstslit.

According to a further feature of the present invention, the secondblade element is restrained from pivotal movement when the second bladeassembly assumes the closed position.

According to a further feature of the present invention, the secondblade assembly is resiliently biased towards the open position.

There is also provided according to the teachings of the presentinvention, a surgical tool for forming a self-sealing flap in tissue ofa wall of a hollow organ and extracting a tissue block from the wall,the surgical tool comprising: (a) a first blade assembly including: (i)a first elongated support element having a first direction ofelongation, and (ii) a first blade element pivotally mounted on thefirst support element so as to be pivotable about a first axisperpendicular to the first direction of elongation, the first bladeelement including a first front blade configured for cutting a firstforward slit parallel to the first axis during advancing of the tool,and a first rear blade with at least one deflecting feature configuredfor forming a first reverse slit diverging from the first forward slitduring withdrawal of the tool along the first forward slit; (b) a secondblade assembly including: (i) a second elongated support element havinga second direction of elongation, and (ii) a second blade elementpivotally mounted on the second support element so as to be pivotableabout a second axis perpendicular to the second direction of elongation,the second blade element including a second front blade configured forcutting a second forward slit parallel to the second axis duringadvancing of the tool, and a second rear blade with at least onedeflecting feature configured for forming a second reverse slitdiverging from the second forward slit during withdrawal of the toolalong the second forward slit; and (c) a mechanical linkageinterconnecting between the first elongated support element and thesecond elongated support element so as to define a range of relativemovement between a closed position in which the first blade assembly isclosed against the second blade assembly and an open position in whichthe first blade assembly and the second blade assembly are spaced apart.

According to a further feature of the present invention, the first bladeassembly and the second blade assembly are configured such that, when inthe closed position, the first blade element and the second bladeelement are restrained against pivotal movement.

According to a further feature of the present invention, each of thefirst elongated support element and the second elongated support elementincludes a fork portion formed with two projecting arms, the first andsecond blade elements being mounted between the projecting arms.

According to a further feature of the present invention, a distalportion of each of the projecting arms is formed as a blade parallel tothe direction of elongation.

According to a further feature of the present invention, the bladeelement further includes a pair of side blades extending along amajority of a length between the front blade and the rear blade in adirection substantially perpendicular to the axis.

According to a further feature of the present invention, the bladeelement further includes an opening substantially circumscribed by thefront blade, the rear blade and the pair of side blades.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 is a schematic cross-sectional representation of the structure ofan eye;

FIG. 2 is an enlarged schematic cross-sectional representation of aregion around the angle of the eye;

FIG. 3 is an isometric view of a first preferred embodiment of asurgical tool, constructed and operative according to the teachings ofthe present invention, for forming a self-sealing flap in tissue of awall of a hollow organ and extracting a tissue block from the wall;

FIG. 4 is an enlarged view of a distal portion of the tool of FIG. 3;

FIGS. 5A, 5B and 5C are isometric, top and rear views, respectively, ofan anterior blade element from the tool of FIG. 3;

FIGS. 6A, 6B, 6C and 6D are upper isometric, lower isometric, top andside cross-sectional views, respectively, of a posterior blade elementfrom the tool of FIG. 3;

FIG. 6E is a cross-section taken along the line I-I in FIG. 6D;

FIG. 7A is an isometric view of an upper support element for supportingthe anterior blade element of FIGS. 5A-5C;

FIG. 7B is an enlarged isometric view of the distal portion of the uppersupport element of FIG. 7A;

FIG. 8A is an isometric view of a lower support element for supportingthe posterior blade element of FIGS. 6A-6E;

FIG. 8B is an enlarged isometric view of the distal portion of the lowersupport element of FIG. 8A;

FIGS. 9A and 9B are side views of the distal portion of the tool of FIG.3 in a closed state and an open state, respectively;

FIGS. 10A and 10B are isometric views of the distal portion of the toolof FIG. 3 in a closed state and an open state, respectively;

FIGS. 11A, 11B, 11C and 11D are schematic cross-sectional views of theangle of the eye illustrating a sequence of incisions used according toone preferred implementation of the method of the present invention;

FIGS. 12A, 12B, 12C, 12D and 12E are schematic side view representationsof a sequence of positions assumed by the tool of FIG. 3 duringimplementation of the method of FIGS. 11A-11D;

FIG. 13 is a schematic isometric view of a block of tissue cut by themethod of FIGS. 11A-11D;

FIG. 14 is an isometric view of a second preferred embodiment of asurgical tool, constructed and operative according to the teachings ofthe present invention, for forming a self-sealing flap in tissue of awall of a hollow organ and extracting a tissue block from the wall;

FIG. 15 is an enlarged isometric view of a distal tool head of the toolof FIG. 14 with the tool head in a closed state;

FIG. 16 is a lower isometric view of the tool head of FIG. 15 in an openstate;

FIG. 17 is an isometric view of an elongated support element from thetool head of FIG. 15;

FIG. 18 is an isometric view of a posterior blade element from the toolhead of FIG. 15;

FIG. 19 is a front isometric view of a lever arm from the tool head ofFIG. 15;

FIG. 20 is an isometric view of a lever mechanism from the tool head ofFIG. 15, the mechanism including two lever arms similar to that of FIG.19;

FIG. 21 is an isometric view of an anterior blade element from the toolhead of FIG. 15; and

FIGS. 22A-22D are a series of schematic side cross-sectional viewsillustrating the sequence of operation of the surgical tool of FIG. 14.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a method for extracting a tissue block from thewall of a hollow organ and forming a self-sealing flap in tissue of thewall. Also provided is a preferred example of a surgical tool and acorresponding specific example of implementation of the method of theinvention.

The principles and operation of surgical tools and methods according tothe present invention may be better understood with reference to thedrawings and the accompanying description.

Referring now to the drawings, FIG. 2, an enlarged view of a part of theeye shown in FIG. 1, shows the underlying principles of a surgicalmethod for extracting a tissue block from the wall of a hollow organ andforming a self-sealing flap in tissue of the wall, particularly asapplied to the eye. Thus, in general terms, the method includes formingan elongated slit 10 of substantially constant width extending from anouter surface of the wall into the wall, typically at a shallow angle,so as to at least partially define a self-sealing flap 12, forming aplurality of additional slits so as to define the tissue block 14, andwithdrawing tissue block 14 along the elongated slit 10 such that thefirst elongated slit is temporarily elastically deformed to allowpassage of the tissue block and is then sealed by the self-sealing flap12.

Reference is made herein to a “self sealing flap”. This term is used torefer to an inward-facing flap which has a small-angle edge positionedso as to tend to seal itself against the overlying tissue when exposedto fluid pressure from within the organ. In certain fields of surgery,for example ocular surgery, the use of a self-sealing flap isparticularly valuable in avoiding the need for stitching of the incisionafter completion of the procedure. Preferred flap edge angles forself-sealing flaps are in the range of 15°-25°, and most preferablyabout 17°. It should be noted that the flap angle may be formed by asingle shallow-angle cut together with the internal surface of thehollow organ, or by a first cut followed by a second “undercut” incisionwhich defines the flap edge angle. The flap may be severed at itslateral sides but, more preferably, is left connected to lateral tissuewhich tends to return it to its natural closed position.

As mentioned, the method is believed to be of particular value asapplied to the eye. In this case, the elongated slit 10 preferablyenters at a peripheral region of the cornea so as to allow insertion ofa tool towards the limbus to a position underlying the conjunctiva. Byentering the eye through the non-vascular corneal tissue, all of theaforementioned complications associated with damage to the vasculartissue of the conjunctiva are avoided. At the same time, since theincision is configured with a self-sealing tissue flap, the slit closesimmediately on completion of the procedure to form a water-tight seal.This and other advantages of the method of the present invention will bebetter appreciated in view of the following description.

It should be noted that the method of the present invention as statedgenerally is not limited to implementation with any specific device ortool, or to any specific geometric relation between the location ofentry into the eye and the location from which the tissue block is cut.Thus, for example, in the schematic example of FIG. 2, the entry slit 10is shown near the periphery of the cornea on one side and the tissueblock 14 is shown at the opposite side of the anterior chamber.Nevertheless, by way of a preferred example, the method will now bedescribed with reference to specific implementations as performed by useof tools 20 and 120, constructed and operative according to theteachings of the present invention. Tool 20 and the corresponding methodsteps will be described, respectively, with reference to FIGS. 3-10B and11A-13. Tool 120 and the corresponding method steps will be described,respectively, with reference to FIGS. 14-21 and 22A-22D.

Turning now to the features of tool 20, this is preferably based upon atleast one, and preferably two, blade assemblies each including a bladeelement pivotally mounted on a support element so as to be pivotableabout an axis perpendicular to a direction of elongation of the supportelement. In each case, the blade element includes a rear blade with atleast one deflecting feature configured for forming a slit divergingfrom the path of insertion during withdrawal of the tool along a slit.In certain preferred cases, the blade element also includes a frontblade configured for cutting forward during an advancing motion. Theeffect of this combination will be better understood from the followingdescription with reference to the two preferred embodiments describedherein. Specifically, a first preferred embodiment will be describedwith reference to FIGS. 3-13, while a second preferred embodiment willbe described with reference to FIGS. 14-22.

Turning specifically to the first preferred implementation of surgicaltool 20 shown in FIGS. 3, 4 and 9A-10B, and the corresponding componentsthereof shown in FIGS. 5A-8B, tool 20 here includes a first bladeassembly 22 including a first elongated support element 24 (FIGS. 7A and7B) having a first direction of elongation 26, and a first blade element28 (FIGS. 5A-5C) pivotally mounted on first support element 24 so as tobe pivotable about a first axis 30 perpendicular to direction ofelongation 24. First blade element 28 includes a first front blade 32configured for cutting a first forward slit parallel to the first axisduring advancing of the tool, and a first rear blade 34 with at leastone deflecting feature 36 configured for forming a reverse slitdiverging from the first forward slit during withdrawal of the toolalong the first forward slit. Deflecting feature 36, and other similardeflecting figures mentioned herein, are most simply implemented as abent-over pointed extension of the blade as shown. Nevertheless, it willbe clear to one ordinarily skilled in the art that various other formsof deflecting feature may readily be substituted for the form shownhere.

Tool 20 further includes a second blade assembly 40 including a secondelongated support element 42 (FIGS. 8A and 8B) having a second directionof elongation 44 and a second blade element 46 (FIGS. 6A-6E) pivotallymounted on second support element 42 so as to be pivotable about asecond axis 47 perpendicular to the second direction of elongation 44Second blade element 46 includes a second front blade 48 configured forcutting a second forward slit parallel to the second axis duringadvancing of the tool, and a second rear blade 50 with at least onedeflecting feature 52 configured for forming a reverse slit divergingfrom a forward slit (typically the first forward slit formed by thefirst blade assembly 22) during withdrawal of the tool along the slit.

First elongated support element 24 and second elongated support element42 are interconnected by a mechanical linkage 54 so as to define a rangeof relative movement between a closed position (FIGS. 9A and 10A) inwhich first blade assembly 22 is closed against second blade assembly 40and an open position (FIGS. 9B and 10B) in which first blade assembly 22and second blade assembly 42 are spaced apart. In the case illustratedhere, elongated support elements 24 and 42 are integrally formed withhandle portions 62 proximal to mechanical linkage 54. Tool 20 ispreferably resiliently biased towards the open position of FIGS. 913 and10B, optionally by a spring biasing of handle portions 62 such as isshown here. In this case, closing of the tool is performed manually bysqueezing the handles together. Clearly, other actuation mechanismsknown in the art may be used. Optionally, the actuation mechanismincludes a self-locking configuration to selectively retain the tool inthe closed position until released by the practitioner.

It should be appreciated that the structure of a single blade assembly22 is a useful tool even if used alone, without the second bladeassembly and mechanical linkage. Specifically, the structure may beinserted into tissue so that front blade 32 cuts an elongated slit alonewhich the assembly advances. Then, on withdrawal of the assembly,deflecting feature 36 lodges in the tissue of the slit and causes rearblade 34 to form a second undercut slit rearwardly diverging from thefirst elongated slit so as to at least partially define a self-sealingflap. Nevertheless, as will be explained, a preferred implementation ofa tool including two blade assemblies with a mechanical linkage andvarious additional features to be described is believed to offer aparticularly advantageous mode of operation for a surgical procedure, aswill be detailed with reference to FIGS. 11A-11D and 12A-12E below.

Preferably, blade assemblies 22 and 40 are configured such that, when inthe closed position, blade elements 28 and 46 are restrained againstpivotal movement. In a basic implementation in which a single bladeassembly is used, pivotal restraint may be achieved by providing adedicated abutment element (not shown) mechanically interconnected withthe elongated support element so as to be movable relative thereto. Theabutment element is then selectively deployable so as to restrain orallow pivotal movement of the blade element.

In the preferred case shown here, the “abutment element” for each bladeassembly is preferably provided by the opposing blade assembly.Specifically, the blade assemblies are configured here to provide directabutment of the lower surface of blade element 28 with the upper surfaceof blade element 46, thereby locking both blade elements against pivotalmovement when closed.

In a preferred implementation, elongated support elements 24 and 42 bothinclude a fork portion formed with two projecting arms, thecorresponding blade elements 28 and 46 being mounted between theprojecting arms. In the case of first elongated support element 24, theextremities of the fork portion are here implemented as sharpened bladeedges so that they cut together with front blade 32 during forwardincision to form a slit. Optionally, the form of engagement betweenblade elements 28 and 46 and the respective fork portions may be shapedso as to limit rotation of the blade elements to a predetermined angularrange, typically from the “straight” position to an angle of about 30°.

It should be noted in this context that the “direction of elongation”for each support element is taken to be the direction of elongation ofthe support portion of the element adjacent to the blade element. Thus,in this case, the direction of elongation for each support element isdefined by the extensional direction of the projecting arms of the fork.

In the preferred embodiment shown here, both support element 42 andblade element 46 differ significantly from the corresponding elements offirst blade assembly 22. Specifically, support element 42 is here formedwith a distal portion of each of the projecting arms providing adownward facing blade edge 56 extending parallel to the direction ofelongation. Blade element 46 is similarly formed with a pair of sideblades 58 extending along a majority of a length between front blade 48and rear blade 50 in a direction substantially perpendicular to axis 47.Front blade 48, rear blade 50 and pair of side blades 47 preferablysubstantially circumscribe an opening 60.

Turning now to FIGS. 11A-13, the operation of tool 20 and acorresponding preferred method of the present invention will now bedescribed.

A shown in FIG. 11A, tool 20 is first inserted into the tissue at ashallow angle (preferably no more than about 25°) to form a firstelongated slit A₁₋₂. At this stage, tool 20 is in its closed state asshown in FIG. 12A so that front blade 32 and sharpened extremities ofthe fork portion of first blade assembly 22 cut a flat slit along whichthe closed distal end of the tool advances. Slit A₁₋₂ is preferablyformed to a maximum depth sufficiently small to render the tool visiblethrough overlying tissue, and typically no more than about 0.2 mm. As aresult of the form of tool 20, the slit exhibits a substantiallyconstant width. For ocular applications, the total width of tool 20, andhence also of the first elongated slit, is preferably less than about 5mm.

Next, tool 20 is drawn back along the first elongated slit whilesimultaneously being gently biased towards its open state. During thismotion, deflecting feature 52 of second blade assembly 40 lodges in thewall of the first elongated slot and starts to form a second undercutslit B₂ from a first position along the first elongated slit so as tofurther define a self-sealing flap 100 (FIG. 11B). The form ofdeflecting feature 52 tends to guide rear blade 50 to form slit B₂ as anarcuate slit. At the same time, the sharpened side blades 58 which forma chord partially within the arcuate path, as well as blade portions 56of the lower fork, start to cut side slits B₃. First blade assembly 22,biased upwards by the opening bias applied to tool 20, follows the pathof the first elongated slit in reverse, designated B₁. The motion oftool 20 at this stage is shown in FIG. 12B.

At the end of the withdrawing motion, after second blade element 46penetrates the inner surface of the organ wall, the opening bias of thetool is further released to force the fork portion of second supportelement 42 inwards. This movement is accompanied by further cutting byblade portions 58 in direction B₃ to form a pair of side cuts below thefirst elongated slit, thereby defining sides of the tissue block. Thecorresponding tool motion is shown in FIG. 12C. This preferably bringsthe entirety of second blade element 40 to a position beyond the innersurface of the tissue wall.

Next, tool 20 is again advanced along a path similar to its initialinsertion path as shown in FIG. 11C. In this case, first blade element28 follows a path C₁ substantially the same as initial path A₁. Secondblade element 46, on the other hand, is now located on the inner side ofthe tissue wall and advances along a path C₂. In the case of thepreferred ocular application, this movement brings second blade element46 into engagement with tissue at or near the angle of the eye where anadditional slit C₂ is cut, thereby defining including a region oftrabecular tissue within the block cut. It is this cut which isparticularly critical in defining the parameters of the surgicaltreatment for glaucoma in ocular applications. This tool movement isshown in FIG. 12D.

Finally, as shown in FIG. 11D, the tool is again withdrawn, this timewith a downward levering motion and a bias applied towards its closedposition. This results in the deflection feature 36 of first bladeelement 28 becoming lodged in the tissue of the first elongated slit soas to cut a third slit diverging from the first slit so as to form adistal cut of the tissue block. This tool motion is illustrated in FIG.12E. The closing action of the tool also serves to grasp the cut tissueblock between the two blade assemblies. The block is then typicallywithdrawn by pulling the tool together with the included tissue blockout along the first elongated slit. The elasticity of the tissue istypically such that the tool and contained block pass relatively easilyby temporary stretching of the tissue. After removal of the tool, thetissue returns resiliently to its relaxed state in which self-sealingflap 100 provides a seal against fluid leakage.

FIG. 13 shows a typical form of the tissue block cut by the preferredimplementation of the present invention. The various faces of the blockare labeled here with the corresponding letters used to designate thecuts of FIGS. 11A-D. The surface labeled C₂ corresponds in part to thenatural inner surface of the cornea.

Turning now to the second preferred embodiment of the present invention,surgical tool 120 will be described with reference to FIGS. 14-22.Generally speaking, tool 120 bears a number of structural similaritiesto tool 20 described above and performs an almost identical sequence ofincisions. A number of significant structural differences, however,render the structure of tool 120 particularly simple to manufacture andto operate.

Turning now to the structure of tool 120, FIG. 14 shows a handleterminating in a tool head 122. Tool head 122, of which the structureand components are better seen in FIGS. 15-21, includes an elongatedsupport element 124 having a direction of elongation 126. Supportelement 124, which is typically a forked formation similar to element 24or 42 described above, is configured for insertion along a first slitparallel to the direction of elongation 126 into the tissue of the wall.A proximal (as held) or posterior (as inserted) blade element 128 ispivotally mounted on support element 124 so as to be pivotable about anaxis 130 perpendicular to direction of elongation 126. Blade element 128includes a rear blade 132 with at least one deflecting feature 134configured for forming a second slit diverging from the first slitduring withdrawal of the tool along the first slit, thereby forming aself-sealing flap in the tissue of the wall.

Unlike tool 20, blade element 128 is here preferably mounted on supportelement 124 via a lever mechanism which is configured to allowdisplacement of blade element from an “in-plane” position (FIG. 16) toan “out-of-plane” position (FIG. 17). The terms “in-plane” and“out-of-plane” are used here to refer to the position of axis 130relative to a “tool plane” passing through support element 128 andparallel to both direction of elongation 126 and axis 130. Thus, in the“in-plane” position, axis 130 lies substantially within the tool planewhereas, in the “out-of-plane” position, axis 130 is displaced so as tobe parallel to, but removed from, the tool plane.

In the preferred implementation shown here, the lever mechanism isimplemented using a pair of lever arms 136 each having a first end 138pivotally engaged with support element 124 and a second end 140pivotally engaged with blade element 128. The lever arms are preferablyinterconnected by a retention element in the form of a bar 141. Thestructure and function of bar 141 will be described further below.

Each lever arm 136 is preferably configured such that, when bladeelement 128 assumes its out-of-plane position, a distal edge of thelever arms presents a blade edge 142 extending substantiallyperpendicular to the tool plane and oriented for cutting parallel todirection of elongation 126. Blade element 128 also preferably includesa front blade 143 configured for cutting a slit parallel to the toolplane during advancing of the tool along the first slit. The function ofthese blades will be described further in the context of FIGS. 22C and22D below.

Preferably, the position of lever arms 136 in the out-of-plane positionis substantially perpendicular to the tool plane. A lock element 144(best seen in FIG. 16) is preferably deployed to retain blade element128 in the out-of-plane position once opened. This may be implementedsimply as shown here as a resilient tab 144 which lodges behind one orboth of the lever arms as they rotate to their open positions.

A further preferred feature of tool 120 is a resilient biasing element146 associated with the lever mechanism and deployed such that, whenblade element 128 assumes its out-of-plane position, biasing element 146biases blade element 128 to a position with the main generally-flatportion of its upper surface substantially parallel to the tool plane.In the implementation illustrated here, resilient element 146 isimplemented as a leaf spring which is initially held in a curved formbetween the rounded bottom end of lever arm 136 and an opposing concavefacet 148 of blade element 128. The leaf spring is biased to tend toreturn to a straight configuration so that, when the blade element islowered to the out-of-plane position and is not otherwise restrained,the blade element is brought to the aforementioned parallel orientation.In the initial in-plane position, blade element 128 is prevented fromflipping upwards by a crossbar 150 as seen in FIG. 15. Preferably,crossbar 150 also serves a locking function during assembly of tool 120by fixing the distance between sides of the fork assembly so that theelements inserted between them by outward flexing of the fork structurecannot subsequently slip out.

Finally, tool 120 also preferably includes a distal (anterior) bladeelement 152 pivotally mounted on support element 124 distally withrespect to blade element 128. Distal blade element 152 is pivotableabout a second axis 154 parallel to axis 130. Blade element 152 has arear blade 156 with at least one deflecting feature 158 configured forforming an additional slit diverging from the first slit duringwithdrawal of the tool along the first slit. The front edge 160 ofdistal blade element 152 is most preferably rounded so as not tounintentionally extend the first slit beyond a precut length.

In order to prevent premature rotation of distal blade element 152 aboutits axis 154, the tool head structure is preferably configured such thatpivotal movement of blade element 152 is limited at least until proximalblade element 128 moves out of its in-plane position. In the exampleshown here, this is achieved by abutment between a surface of bladeelement 152 and a retention element (aforementioned retention bar 141)as will now be described in the context of operation of tool 120.

Turning now to the sequence of operation of tool 120, it is a preferredfeature of the method of the present invention as performed by thisembodiment that the initial slit for insertion of the tool is performedby a separate surgical tool (not shown) prior to insertion of tool 120,while the front edge of distal blade element 152 and the ends of supportelement 124 are rounded to avoid unintended elongation of the slit. Thisallows exact predetermination of the extent of the incision usingconventional techniques, thereby rendering the subsequent procedure lessdelicate.

After cutting the initial slit, tool head 112 is preferably fullyinserted along the slit while covered by a protective sleeve, such as ofTeflon, which is then withdrawn. The resulting initial placement of toolhead 112 is then as represented in FIG. 22A. The tool is then withdrawn(i.e., to the right as shown). During this motion, the deflectingfeature 134 of proximal blade 128 becomes lodged in the tissue andguides rear blade 132 downwards to for an undercut slit as shown in FIG.22B, thereby creating a small-angle self-sealing tissue flap asdescribed in the first embodiment. The motion also draws down lever arms136 with blade element 128 as shown. As the rearward motion continues,the tissue at the sides of the slit applies pressure to the flat rearedges of the lever arms, thereby tending to open them further. Thiseffect combined with the effect of biasing element 146 ensure that, whenblade element 128 penetrates the inner surface of the tissue, lever arms136 swing to their perpendicular open positions and blade element 128return to their orientation parallel to the tool plane as shown in FIG.22C. From this point on, lever arms 136 are locked in this open positionby lock elements 144.

Parenthetically, the operation of retention bar 141 is also clearlyillustrated by FIGS. 22A-22C. Initially, the rear blade of distal bladeelement 152 is lodged above bar 141. This prevents blade element 152from cutting into the underlying tissue during the withdrawal motiondescribed. As lever arms 136 swing down, the eccentrically mountedretention bar 141 shifts until, near the fully open position, it clearsblade element 152, thereby allowing pivotal motion.

The next step is a second forward movement. This time, as supportelement 124 advances along the first slit, blade edges 142 of lever arms136 cut side faces of the tissue block. Similarly, when front blade 143of blade element 128 encounters tissue (e.g. at the angle of the eye),it continues into the tissue, cutting a lower surface of the tissueblock. This movement continues until the blunt end of support element124 and/or the rounded front edge 160 of distal blade 152 reaches thepredefined end of the first slit.

The tool is then withdrawn a second time alone the first slot. Thistime, distal blade element 152 is clear of retention bar 141 and istherefore free to pivot. As a result, deflecting feature 158 becomeslodged in the tissue as shown in FIG. 22D and deflects blade element 152downwards to cut a distal surface of the tissue block. The substantiallysevered tissue block is then substantially contained by distal bladeelement 152 at its distal end, by proximal blade element 128 from below,by lever arms 136 at the sides, and by retention bar 141 and crossbar150 from above. Tool 120 is then withdrawn (by temporary stretching ofthe tissue) along the insertion slot with the tissue block retainedtherein. On removal of the tool, the tissue springs back to itsundeformed state in which the small-angle flap seals the incision.

Preferably, a shoehorn-shaped tool (not shown) is inserted along thefirst slit underneath tool 120 prior to its final withdrawal so as tominimize abrasive irritation or damage to the tissue along the faces ofthe slot.

A range of further modifications to the device of the present inventionwill be clear to one ordinarily skilled in the art. For example, thedevice may be modified by wiring to an external remote electrical powersource as is known in the art to perform local cauterization of cuttissue by heating of part or all of one or more blades during orsubsequent to the cutting operations.

It will be appreciated that the above descriptions are intended only toserve as examples, and that many other embodiments are possible withinthe broad scope of the present invention as defined by the appendedclaims

1. A surgical tool for forming a self-sealing flap in tissue of a wallof a hollow organ during a procedure for extracting a tissue block fromthe wall, the surgical tool comprising a tool head including: (a) anelongated support element having a direction of elongation andconfigured for insertion along a first slit parallel to said directionof elongation into the tissue of the wall; and (b) a blade elementpivotally mounted on said support element so as to be pivotable about anaxis perpendicular to said direction of elongation, said blade elementincluding a rear blade with at least one deflecting feature configuredfor forming a second slit diverging from said first slit duringwithdrawal of the tool along the first slit, thereby forming aself-sealing flap in the tissue of the wall.
 2. The surgical tool ofclaim 1, wherein a plane passing through said support element parallelto both said direction of elongation and said axis is referred to as atool plane, and wherein said blade element is mounted on said supportelement via a lever mechanism, said lever mechanism being configured toallow displacement of said blade element from an in-plane position inwhich said axis lies substantially within said tool plane to anout-of-plane position in which said axis is displaced so as to beparallel to, but removed from, said tool plane.
 3. The surgical tool ofclaim 2, wherein said lever mechanism includes a pair of lever arms eachhaving a first end pivotally engaged with said support element and asecond end pivotally engaged with said blade element.
 4. The surgicaltool of claim 3, wherein said lever arms are configured such that, whensaid blade element assumes said out-of-plane position, at least part ofeach of said lever arms presents a blade edge extending substantiallyperpendicular to said tool plane and oriented for cutting parallel tosaid direction of elongation.
 5. The surgical tool of claim 2, whereinsaid lever mechanism further includes a lock element configured toretain said blade element in said out-of-plane position.
 6. The surgicaltool of claim 5, wherein said blade element has a substantially planarupper surface, the lever mechanism further including a resilient biasingelement deployed such that, when said blade element assumes saidout-of-plane position, said biasing element biases said blade element toa position with said upper surface substantially parallel to said toolplane.
 7. The surgical tool of claim 6, wherein said blade elementfurther includes a front blade configured for cutting a slit parallel tosaid tool plane during advancing of the tool along the first slit. 8.The surgical tool of claim 7, wherein said blade element is referred toas said first blade element, and wherein said axis is referred to assaid first axis, the tool head further including a second blade elementpivotally mounted on said support element distally with respect to saidfirst blade element, said second blade element being pivotable about asecond axis parallel to said first axis, said second blade elementincluding a rear blade with at least one deflecting feature configuredfor forming an additional slit diverging from said first slit duringwithdrawal of the tool along the first slit.
 9. The surgical tool ofclaim 8, wherein said lever mechanism further includes a retentionelement deployed such that, when said blade element assumes saidin-plane position, said retention element abuts a surface of said secondblade element so as to limit pivotal movement of said second bladeelement about said second axis and, when said blade element assumes saidout-of-plane position, said retention element is removed from saidsecond blade element so as not to limit pivotal movement of said secondblade element about said second axis.
 10. The surgical tool of claim 1,wherein said elongated support element includes a fork portion formedwith two projecting arms, said blade element being mounted between saidprojecting arms.
 11. The surgical tool of claim 10, wherein a distalportion of each of said projecting arms is formed as a blade parallel tosaid direction of elongation.
 12. The surgical tool of claim 1, whereinsaid blade element further includes a pair of side blades extendingalong a majority of a length between said front blade and said rearblade in a direction substantially perpendicular to said axis.
 13. Thesurgical tool of claim 12, wherein said blade element further includesan opening substantially circumscribed by said front blade, said rearblade and said pair of side blades.
 14. The surgical tool of claim 1,further comprising a blade control assembly including at least oneabutment element mechanically interconnected with said elongated supportelement so as to be movable relative to said elongated support elementbetween a closed position in which said at least one abutment elementabuts said blade element so as to restrain pivotal movement of saidblade element and an open position in which said abutment element isremoved from said blade element so as to allow pivotal movement of saidblade element.
 15. The surgical tool of claim 14, wherein said at leastone abutment element is implemented as a second blade assemblyincluding: (a) a second elongated support element having a seconddirection of elongation; and (b) a second blade element pivotallymounted on said second support element so as to be pivotable about asecond axis perpendicular to said second direction of elongation. 16.The surgical tool of claim 15, wherein said second blade elementincludes a second front blade configured for cutting a primary slitparallel to said second axis during advancing of the tool into thetissue of the wall, and a second rear blade with at least one deflectingfeature configured for forming a secondary slit diverging from saidprimary slit during withdrawal of the tool along the first slit.
 17. Thesurgical tool of claim 15, wherein said second blade element isrestrained from pivotal movement when said second blade assembly assumessaid closed position.
 18. The surgical tool of claim 15, wherein saidsecond blade assembly is resiliently biased towards said open position.19. A surgical tool for forming a self-sealing flap in tissue of a wallof a hollow organ and extracting a tissue block from the wall, thesurgical tool comprising: (a) a first blade assembly including: (i) afirst elongated support element having a first direction of elongation,and (ii) a first blade element pivotally mounted on said first supportelement so as to be pivotable about a first axis perpendicular to saidfirst direction of elongation, said first blade element including afirst front blade configured for cutting a first forward slit parallelto said first axis during advancing of the tool, and a first rear bladewith at least one deflecting feature configured for forming a firstreverse slit diverging from said first forward slit during withdrawal ofthe tool along the first forward slit; (b) a second blade assemblyincluding: (i) a second elongated support element having a seconddirection of elongation, and (ii) a second blade element pivotallymounted on said second support element so as to be pivotable about asecond axis perpendicular to said second direction of elongation, saidsecond blade element including a second front blade configured forcutting a second forward slit parallel to said second axis duringadvancing of the tool, and a second rear blade with at least onedeflecting feature configured for forming a second reverse slitdiverging from said second forward slit during withdrawal of the toolalong the second forward slit; and (c) a mechanical linkageinterconnecting between said first elongated support element and saidsecond elongated support element so as to define a range of relativemovement between a closed position in which said first blade assembly isclosed against said second blade assembly and an open position in whichsaid first blade assembly and said second blade assembly are spacedapart.
 20. The surgical tool of claim 19, wherein said first bladeassembly and said second blade assembly are configured such that, whenin said closed position, said first blade element and said second bladeelement are restrained against pivotal movement.
 21. The surgical toolof claim 19, wherein each of said first elongated support element andsaid second elongated support element includes a fork portion formedwith two projecting arms, said first and second blade elements beingmounted between said projecting arms.
 22. The surgical tool of claim 21,wherein a distal portion of each of said projecting arms is formed as ablade parallel to said direction of elongation.
 23. The surgical tool ofclaim 19, wherein said blade element further includes a pair of sideblades extending along a majority of a length between said front bladeand said rear blade in a direction substantially perpendicular to saidaxis.
 24. The surgical tool of claim 23, wherein said blade elementfurther includes an opening substantially circumscribed by said frontblade, said rear blade and said pair of side blades.